When a subscriber calls another through a mobile communication network, a terminating exchanger on the network provides the caller with a uniform ringback tone.
Since the ringback tone is same all the time, a caller can not identify a called before the called answers. Furthermore, the uniform ringback tone can not satisfy various subscribers' needs to reveal their personality.
By the way, various ad methods are being proposed in these days. One of these ad methods is to send an ad sound message to a caller instead of a conventional RBT. However, such an ad sound message is chosen unilaterally by a network operating enterprise. If a caller heard such a unilateral ad sound he or she could talk over a mobile telephone with a called for a limited time.
However, the method that an ad sound is provided instead of a conventional ringback tone still has the aforementioned drawbacks. That is, a caller can not identify a called before the called answers and the uniform RBT can not satisfy various subscribers' needs to reveal their personality.
To satisfy such needs of subscribers, a called-based RBT replacement service has been proposed by the same applicant of this invention as Korean patent application whose number and filing date are 10-2002-010006 and Feb. 25, 2002, respectively.
In the proposed method, an arbitrary sound chosen by a called who has subscribed to the RBT replacement service is provided for a calling subscriber instead of a conventional RBT.
However, if a called is not a subscriber of the RBT replacement service, a caller hears inevitably a dry conventional RBT although he or she has been subscribed to the RBT replacement service.